Definition

Myasthenia gravis (MG) is an autoimmune disorder. The signal from the nerves to the muscles is blocked. As a result, the muscle cannot move and become increasingly weaker.

Symptoms may grow more severe over time. This is a potentially serious condition. MG requires care from your doctor. If you suspect you have this condition, contact your doctor immediately.

Causes

The root cause of MG is unknown. It occurs when the body’s immune system attacks receptors in muscle. Normally, these receptors respond to the chemical acetylcholine (ACh). This chemical allows nerve signals to prompt the muscles to move. When the immune system prevents these receptors from working well, the muscles cannot respond to nerve signals.

The thymus is thought to play a role in some cases of MG. The thymus is an organ behind the breastbone. Immune proteins called antibodies are produced there. It is these antibodies that may target the ACh receptors. It is still not clear why the thymus begins to produce these.

Infants of mothers with MG are more likely to develop a temporary form. It is called neonatal MG. The mother’s abnormal antibodies enter the baby’s bloodstream. When the baby is born, there may be muscle weakness. The abnormal antibodies are often cleared from the baby in about two months. This will end the baby’s symptoms.

Risk Factors

The following factors increase your chance of developing MG:

Sex and age:

Women between the ages of 10—30

Men between the ages of 50—60

People with certain genetic markers, called HLA-B8, DR3

Symptoms

Symptoms include:

Muscle weakness that increases with muscle use/exercise, and improves after resting those muscles

Removal of the thymus gland is recommended for most patients with MG. This surgery may improve the symptoms in some patients.

Mechanical Ventilation

This may only be needed if breathing is severely impaired. This can happen during an episode of myasthenic crisis.

Physical and Occupational Therapy

Therapy does not generally alter the course of the disease. It may be needed to help the patient cope with changes in muscle strength. It may also help with learning alternative ways to approach daily activities.

Prevention

There are no known ways to prevent MG. The following steps may improve muscle functioning in people who already have the condition:

Avoid medicines that may worsen MG, such as:

Beta-blockers

Aminoglycoside antibiotics

Quinolone antibiotics

Class I medications used for abnormal heart rhythms

Treat any infections promptly.

If you have trouble swallowing, please notify your doctor immediately. You may wish to consult a dietitian to help you construct a healthy diet that is easier to swallow.

If you have trouble speaking, you may wish to consult a speech therapist.

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY.
Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.